Agricultural advances caused the world's population to grow from 170 million during the Roman period 2,000 years ago to 900 million in 1800. By 1900 the industrialisation of large parts of the world had led to a trebling of the world�s population in only 100 years.

This growth in population has increased the stresses on the environment. Larger populations required more resources, which involved a greater intensification of farming and industry. In addition, the rapid population growth associated with industrialisation during the last two centuries has led to considerable depletion of raw materials (most notably fossil fuels, metals and stone) extracted from the Earth. Furthermore, as we consume more and more resources, we are accumulating waste at an alarming pace.

Today, the world's population stands at 6 billion. This is expected to almost double within the next 50 years. Most of this increase is due to occur in the developing world. One in five people alive today are desperately poor and each year 40 million die from malnutrition and diseases related to poverty (more than 100,000 per day).

Such a large population can be sustained only as long as food resources are properly managed and distributed, and the environmental impacts of agriculture and housing are minimised. By being prepared, population growth and development can be sustained by using sensible planning and suitable modern technology. Agenda 21 recognises that to achieve sustainable development throughout the world, population must be managed and controlled by a process of "demographic dynamics".